The present invention relates to a paper cassette which is inserted in the paper feed mechanism of an electrophotographic printer or the like, and a paper cassette insertion mechanism for such a paper cassette.
FIG. 14 is a vertical section showing a conventional paper cassette 3, and FIG. 15 is a vertical section showing a conventional electrophotographic printer 1 into which the paper cassette 3 of FIG. 14 is inserted.
As shown in FIG. 14, in a conventional paper cassette 3, when paper 6 is to be stacked in the paper cassette 3, a paper stack tray 9 which is free to pivot about an axis 11 in the direction A-B is locked parallel to the baseplate 12. A locking member 15, which is pushed in the cassette insertion direction (direction D) by a compressed coil spring 16, is then engaged with a hook 14 provided on a lower surface of the paper stack tray 9.
When the paper cassette 3 is press-inserted in direction D into the cassette receptacle 4 of a housing 2 of the printer 1, as shown in FIG. 15, a projection 15b on a lower surface of the locking member 15 comes into contact with a stack tray release member 17 provided in the cassette receptacle 4, and the locking member 15 undergoes a relative displacement in the cassette ejection direction (direction C) so that the paper stack tray 9 is no longer locked. The paper stack tray 9 is then pushed upward by a coil spring 13 (direction A) so as to press the paper 6 against the supply roller 7. A paper separating member 10 also comes into contact with the supply roller 7, and when the supply roller 7 rotates, the paper 6 stacked in the cassette 3 is ejected via a paper guide 8 one sheet at a time to the printing assembly 5.
When the paper cassette 3 is removed from the cassette receptacle 4, it is pulled out in the direction C by gripping a tag 18 on the paper cassette 3.
However, in this conventional paper cassette 3, the coil spring 16 is kept compressed while the paper cassette 3 is inserted in the cassette receptacle 4. The coil spring 16 therefore tends to suffer fatigue so that its restoring force in the direction D declines, and the paper stack tray 9 can no longer be locked.
Moreover, as the paper cassette 3 is provided with the hook 14, the locking member 15 and the lock release member 17 on its lower surface, the cassette receptacle 4 has to be thicker, and devices such as printers into which the paper cassette was inserted could not easily be made thin.
Again, in conventional cassette insertion mechanisms, the cassette was removed by gripping the tag 18, so the user's nails sometimes break during the operation.